Air pollution significantly increases the risk of low birth weight in babies, leading to lifelong damage to health, according to a large new study.

According to theguardian.com, the research was conducted in London, UK, but its implications for many millions of women in cities around the world with far worse air pollution are something approaching a public health catastrophe, the doctors involved said.

Globally, two billion children — 90 percent of all children — are exposed to air pollution above World Health Organization guidelines.

A UNICEF study also found that 17 million babies suffer air six times more toxic than the guidelines.

The team said that there are no reliable ways for women in cities to avoid chronic exposure to air pollution during pregnancy and called for urgent action from governments to cut pollution from vehicles and other sources.

Mireille Toledano, at Imperial College London, and who led the new research published in the British Medical Journal (BMJ), said, “It is an unacceptable situation that there are factors a woman cannot control that adversely affect her unborn baby.”

The study analyzed all live births in Greater London over four years —over 540,000 in total — and determined the link between the air pollution experienced by the mother and low birth weight, defined as less than 2.5kg.

The scientists found a 15 percent increase in risk of low birth weight for every additional 5 micrograms per cubic meter (µg/m3) of fine particle pollution.

The average exposure of pregnant women in London to fine particle pollution is 15µg/m3, well below UK legal limits but 5µg/m3 higher than the WHO guideline.

Cutting pollution to that guideline would prevent 300-350 babies a year being born with low weight, the researchers estimated.

Toledano said, “The UK legal limit is not safe and is not protecting our pregnant women and their babies.

“We know that low birthweight is absolutely crucial. It not only increases the risk of the baby dying in infancy, but it predicts lifelong risk of diabetes, cardiovascular disease etc.

“You are setting in stone the whole trajectory of lifelong chronic illness.”

The new research shows the impact of air pollution on babies in London is significant, but affects a relatively small number — only about 2.5 percent of all full-term babies are born with low weight.

However, many cities around the world — such as Delhi in India — suffer far higher levels of toxic air, raising concerns of huge impacts on unborn babies.

Sarah Stock and Tom Clemens, from the University of Edinburgh, in a BMJ editorial said, “Though the new results from the UK are concerning, a global perspective reveals something approaching a public health catastrophe.

“The pregnancy effects of extreme exposure environments like Delhi are unmeasured, and there is an urgent need to turn attention to such environments where large numbers are at considerable risk of harm.”

Stock said that outdoor air pollution is already causing millions of early deaths every year among adults and children, “And that is not taking into account deaths in utero or resulting from exposure in pregnancy, because we just don’t have the data yet.”